I really like Chiang Mai. I haven't been to Manila, but from what I've read, it sounds like Chiang Mai is a nicer place to live. It's very cheap and has very fast internet. I think it's also very safe, especially late at night. (Apart from the roads, which are very dangerous compared to other countries.)

English is not a problem at all. You can get by with English at many (if not most) restaurants, shops, apartments, lawyers, accountants, hospitals, dentists, etc. etc.